2.0 Analysis 2.1 Introduction The aircraft overran the end of the runway by about 340 feet at approximately 30 knots. The ground past the end of Runway 25 was soft, causing the aircraft to decelerate quickly. Damage to the aircraft was minimal. The analysis will discuss the probable reasons for the overrun, specifically addressing the following topics: landing long, the effect of the snow on the runway, the braking friction performance, the techniques used by the crew, and the communication between the crew and the Windsor tower controller. 2.2 Approach and Landing The ceiling and the visibility at Windsor Airport were low enough that flying other than a precision approach would probably not result in a landing. The wind favoured Runway 07; however, only a non-precision, circling, non-directional beacon approach was available to Runway 07. Thus, the decision was made to fly the ILS approach to Runway 25 and land with a 4-knot tailwind. Landing with a tailwind caused an increase in the landing distance. The flight crew flew a stable approach to the decision height. Considering all landing parameters, including the tailwind, performance charts indicate that sufficient runway would have been available to stop the aircraft on a bare, dry runway had the aircraft been landed at the normal touchdown point of about 1000 feet from the threshold. The long landing contributed directly to the overrun. A number of factors contributed to the delayed touchdown. From the decision height, where the autopilot was disengaged in accordance with standard operating procedures, the aircraft was flown an average of 6 knots faster than the normal approach speed, and it crossed the threshold about 20 feet higher than the normal 50 feet agl. The task of landing the aircraft was more difficult than normal, given the instrument meteorological conditions, the darkness, and the flight crew's relative unfamiliarity with the aerodrome. 2.3 Stopping Performance When the captain used the performance charts to calculate the required landing distance, he assumed that braking action would be normal. The calculated factored landing distance was 6890 feet, based on a firm touchdown within 984 feet of the threshold, minimum delay for nose lowering, spoiler deployment, thrust reverser deployment, and sustained maximum antiskid braking until stopped. Although the aircraft landed long, based on the calculation done by the captain for a bare, dry runway, the aircraft should have been able to stop within the remaining runway available, because the unfactored stopping distance was 3280 feet. However, referencing CRFI Table 2 (Figure 2), the unfactored landing distance of 4125 feet (calculated factored landing distance of 6890 feet divided by 1.67) more than doubles when a CRFI of 0.30 is applied, to approximately 8350feet. Runway 25 has 7850 feet of landing distance available. Based on these numbers, and considering that the aircraft overran the runway by only 340 feet, the aircraft braking action was appreciable. This assessment is corroborated by the fact that two large aircraft (a Hercules C-130 and an Airbus A319) landed in similar conditions within the 22 minutes preceding the occurrence (with one aircraft reporting braking action as moderate), and the fact that an AMS conducted three runway friction evaluation runs just before the overrun, with an average result of 0.30. There were no indications that the aircraft brakes were not functioning normally. Although the centre 120 feet of runway were covered by a trace of loose snow that degraded braking action, the longitudinal deceleration of the aircraft averaged -0.15g throughout the landing roll, even after deactivation of reverse thrust, suggesting that aircraft braking action was considerable. The AN124 left substantial tire skid marks approximately 100 feet before exiting the runway, also indicating appreciable braking action. 2.4 Communications Between ATC and the Flight Crew The word moderate is not standard terminology used to describe braking action. It is used to describe a weather-related condition typically associated with precipitation, icing, or turbulence. International Civil Aviation Organization procedures for air navigation services state that, when describing aerodrome information, the terminology used to report braking action should be relayed using the terms, Good, Medium, Poor, Unreliable, or any combination of these. Although the Air Traffic Control Manual of Operations (ATC MANOPS) recommends passing on reports as they are received, forwarding the non-standard phraseology moderate from the Hercules C130 flight crew to the AN124 flight crew could have possibly induced confusion or misinterpretation on the part of the AN124 flight crew, not being fluent in English. Previous information passed to the crew regarding runway condition and other aircraft landing without incident likely led the crew to believe that braking action was adequate for a normal approach and landing. As initially proposed and acknowledged by the AN124 flight crew, ATC did not follow up on the intention to request a braking action report from the Airbus that landed 10 minutes before the AN124 touched down. This report was to be passed to the AN124 flight crew to enhance their situational awareness of the runway surface. Although the flight crew were aware of snow on the runway, marginal visibility in light snow, and a light tailwind, it cannot be determined if the absence of a braking action report from the Airbus contributed to the outcome of this occurrence. ATC MANOPS provisional directive 9709, supplementing Part I, Article 169, states that ATC must inform concerned aircraft of runway conditions that may affect flight safety and must issue the most recent runway surface condition for the applicable runway as received from the responsible airport authority. The CRFI report of 0.30 issued to ATC by the AMS 16 minutes before this occurrence was not passed on to the AN124 flight crew; however, it was passed to the Airbus flight crew. It was not determined why this communication was not recorded on the AN124 CVR, although the radio operator advised ATC that he would be monitoring the frequency. The AN124 flight crew advised that they would have diverted the aircraft to the alternate airport had they known that the CRFI was below 0.40. 3.0 Conclusions 3.1 Findings as to Causes and Contributing Factors The aircraft touched down 3400 feet past the threshold of Runway 25 and could not be stopped in the remaining 4450feet. Because of the weather minima on Runway 07, the aircraft was landed with a 4-knot tailwind component on Runway 25. The aircraft was about 20 feet higher and about 6 knots faster than recommended when it crossed the threshold of Runway 25. Consequently, the aircraft touched down well beyond the normal touchdown point. The runway was covered with a trace of loose snow, which reduced braking friction and lengthened the landing roll. The Canadian runway friction index (CRFI) report of 0.30, issued to air traffic control by the airport maintenance specialist, was not passed to the AN124 flight crew. This resulted in the flight crew decision to land at Windsor when a diversion to an alternate airport might have been conducted had the flight crew been aware of the CRFI. 3.2 Findings as to Risk At the time of landing, the only information about runway braking action that was passed to the flight crew was that braking action was moderate, a non-standard and perhaps confusing term. Air traffic control did not inform the flight crew of the CRFI of 0.30 or the runway braking action of the Airbus.